Candid discussion and case review with Dr. George Guild and Dr. Steven Nishiyama. See how Dr.Nihiyama performed a robotic-assisted revison knee arthroplasty using the CORI™ Surgical System- the first robotic system to receive a revision indication.
Hello, all and welcome to this presentation of a revision Total Knee arthroplasty performed with the coy robotic knee system utilizing the Smith and Nephews legion revision knee. I'm happy to be here with doctor Steve Nishiyama, who is going to be the operating surgeon. And I'm George Gild and will be the moderator on this case, Steve. You wanna say hello for a second. How you doing everyone? All right, thanks Steve. Once again, I'm George G from Emory University, uh Adult hip and knee reconstruction. And uh Steve is coming to us from Las Vegas, Nevada Desert orthopedics. Um Those are our disclosures. Uh Keep in mind we are consultants for Smith and nephew Steven E C O I to report. No. OK. Excellent, excellent. Um So without further ado uh Steve, if you'll just start describing this case, uh before we get going. Sure. Um This is a very pleasant 80 year old female um that recently came to me just a pretty healthy lady, 80 years old, um peripheral neuropathy and otherwise quite healthy. Um She had a primary total need done by another surgeon here locally um back in April of 2011. Um and started developing the insidious onset of uh uh knee pain, um, definitely had startup pain, um uh concerning for uh loosening of her implants and these are her uh preoperative radiographs, uh which do show uh obvious evidence of loosening, particularly of the tibia component. And it is appearing to drift into various, uh certainly some loosens about the tibia tray universally and, and questionably on the femur. So it looks like we got a loose knee indicated for revision, knee replacement surgery. And briefly if you'll just go through your over overview of the work flow before we get into the details. Sure. And this is, this is a very busy slide here, but really there are five main uh main components to executing the core robotic revision. Um The first is actually the preoperative work up and, and also the case set up and very uh similar if you're familiar with uh utilizing the core robot in in terms of pin placement. And we'll discuss that here in the video. Second is actually the registration um and collecting ligament laxity and uh creating um a, a virtual map of the knee in space. And this is one of the great um uh game changing things with uh the the robot is is that we are actually image free um then the implant planning and gap balancing portion of the procedure and um incorporating the, the ligament laxity to the overall plan. All right, Steve. Now, it looks like before we even started the case, we're looking at a couple of trays. So tell me a little bit about tray management with Corey. Sure, this is a uh unfortunately, it's not AAA full picture of, of everything that's going on here. But What is really game changing here in the setting of revisions is that I'm used to my and my tech and team are, are used to opening 13-15 trays. And what we've done is consolidate it down to only three trays. Um and in addition to a quarry tray. So um my rep and my team have done a good job of consolidating everything down to the ne the necessary instruments to execute uh even uh adding cones. Um We do utilize the, the top of the screen there, the augment tray uh because it's very um in neatly organized, but that's it, it, it is, it is these trays in a singular table and it really um reduces the stress on sterile processing and, and it's obvious has its economic benefits. Um for your hospital agree that it's a lot of cost to just uh get one tray ready. So that's a huge benefit for this system is getting your trays down. Uh It looks like you're just starting incision here just briefly describe, you know, patient position if you use a leg holder, what kind of anesthesia you might be under? Sure. Um In this setting, she's actually have a, has a, a line and spinal, I do use a um a, a uh a bump system um with a lateral post. Um a pretty traditional approach. I do ellipse out the incision and then as you see here, we're just creating a traditional meter Perel arthrotomy. Um The first thing I do is to ensure that the fluid um doesn't look infectious and appearing um just take the arthrotomy up approximately along the quad there. Um and really assessing the joint here and we've jumped ahead here, but you perform a thorough synovectomy uh just to ensure that there is no other substantial pathology and, and we're jumping to pin placement and this is certainly a, a big uh part of um adopting any type of navigation or robotic technology. And um I'm demonstrating here where I typically place uh my pins in the primary setting. But in uh with keeping in mind of having to prepare for a boss and instrument and canals, um we have to keep uh our pins out of that field. And so I've actually gone to a more um medial approach just medial to where the implant is. It uh is, is uh so currently sitting and angle it slightly from media to lateral and uh try to engage by Cory uh sees being very careful not to go too far beyond on the far cortex, obviously, with tiger country being back there, um looks like I extend the incision here slightly. Um and, and place the second pin in line with that. Um And I found that this is a great positioning for the pins and actually can keep them in throughout the entire procedure. Now, Smith and nephew does uh recommend that or at least has its FDA clearance for pin placement to be extra incisional along the diaphysis proximal. Uh keeping in mind the length of the um planned stems. And if you're using a short 1 20 stem, certainly being beyond that, about a centimeter or two in order um to beyond the level of the uh intermediary canal um instruments. Um and the same with the femur. Um one thing that's pretty critical here is actually um my pin uh actually, my arrays are certainly uh much further out wider than that of a primary setting. And so I, I actually angle my arrays slightly more superior. So the camera field of view um can capture it easily. And so throughout the whole arc of motion, um we don't lose the, the femoral um array, then we're gonna move on to the tibia next. And again, keeping in mind of um of staying out of the uh the region of the uh the instrument, the tibia um being again beyond 100 and 20 millimeters. And you can see, I actually go straight through the incision and I use a small little cob band that I place on there and look, I'm, I'm sorry. Uh And then put the ale band over that um in order to prevent any dragging of the aisle bend into the uh incision itself. And I just go straight through with the 3.2 millimeter pin. Um And I found that this is the most aesthetically pleasing and really the easiest um uh to execute the tibia pin placement. And I engage by cortices, you could see here, I'm well beyond the uh anticipated length of the intermediary uh the tibia component. So, um, and then uh I lock it into place. Um, and then make sure that we're, um, certainly within the field of view throughout the whole arc of motion uh for uh the camera. Have you been closing those pin sites at the end or do you need to, uh, you don't need to, I have, I've, um, on on occasions actually just put a sterry ship on there. But, um, my P A does like to add a little belt and suspenders. So she does throw a small, uh three oh, um, a nylon stitch in, in there just to as a, just in case. So, and I've had no uh knock on wood um, pin site issues, uh moving forward. Ok. And are you using these intraarticular trackers or are you doing it some other way? Yeah. So in, in this situation, I'm, I'm certainly, uh you can see that I'm not using, um, uh, some uh uh checkpoints. Um I certainly not recommended on, on behalf of Smith and nephew. But I it's another thing in the surgical field that we have to account for and particularly in the setting of a revision, you know, bone loss and whatever it may be. And the bone is certainly not as good. And so, um, I, I feel that that checkpoint can easily move, but even in the primary setting, I actually use a special point along the arrays as my uh checkpoint throughout the case. And then when you're marking your tibial knee center here, typically it's the post tier fibers of the AC L. How are you figuring that out when there's a polyethylene in place? Yeah. So certainly, you know, fortunately in this case, it's a, it's AC R knee with a dish poly. Um but it's, it's certainly an estimate, right? I'm, I'm trying to visualize where the AC L may have been in the past and um you really giving it a ballpark in the center most point of the, the tibia tray. Now, that's obviously very different in the setting of A P S or a constrained uh polyethylene. And in those situations, I'll actually take a osteotone and just knock off the post and then um mark the center point there as my tibia center. That's a great point, Steve. And if you find that your t tibial center is a little too high, occasionally you have to drill a drill pit and into the polyethylene and, and make sure you get your point low enough and that, that does actually come up uh tell us what's what's going on now with your work flow. So we just, we just collected the hip center uh and then now um mimicking the uh weight bearing by applying an axial load and then taking it through a range motion. Um And then that's all the major registration points. Now, uh we're moving on to uh creating the virtual map. And again, as I mentioned earlier, one of the um really key parts of this technology is is it being image free? What we're doing is essentially creating a virtual image in space um giving the the robot and computer information about the anatomy and and geometry of the um articular surface and it creates a virtual map. Uh My mapping is certainly different in the setting of a revision than that of a um uh a primary knee arthroplasty. Now, uh the con basic concepts are the same, but I actually spend much more time um mapping out the uh condos of the femur going all the way beyond the epi condos, media and lateral um to try to give the robot as much information as possible. And the old adage of any type of um technologies, particularly navigation or robotics is that garbage in uh equates the garbage out. And so I wanna try to give the robot as much um good information as possible and you can see that it's creating quite a um a complete, um, virtual map of the entirety of the distal femur and really also focusing a lot on making sure I go up the diy of the femur to have a good idea of the bow of the femur and accounting for that. Um, uh, when we're placing the anti flee or the implant. Yeah, this looks great. You've really painted far more than what we probably paint for a primary replacement. That's a great point. And also just looking how you're painting it. You know, you're really not coming off implant or bone as you're registering it. So I think, you know, for those, if you're new to Corey, you wanna make sure you're staying on bone and implant that you're not registering uh things that aren't there. And I think meticulous technique is important to make sure you get your sizing correct. Look, I'm seeing some extra points here, Steve, what's going on with that? Yeah. So again, one of the great parts of, of the core robot is actually being able to add special points and that's exactly what it is here. And you can see that I've marked out the media and lot of bacon and this is uh a quite a critical point is is that, you know, we're revising a, a failed total knee and sometimes even malrotation can contribute to that. And so I really wanna define um the trans epi condo axis and, and not rely on the poster condo axis So I, I strongly encourage that doing this. Uh You really manually define the rotation of the fe femur in order to uh plan appropriately. I see you're, you're kind of diving into the intercon or notch here. Uh I assume you're removing some cruciate ligaments, uh what's going on? Yeah, so um this being ac R A knee. Um and as we all know when we again, the whole garbage in garbage out if we plan for the surgery and uh uh plan for the ligament balance. Um But keep the PC O N then later on the case, remove it and we know that the reflection space uh opens up approximately three millimeters. And so, um before we even stress the knee, um I'm gonna resect the, the PC L. Um Certainly if it's A P S N, it's already gone. Um And uh so I take it out there and you can see here that I'm um actually making a demonstration of it. It doesn't really matter if it's a lip poly either. Um You can just treat it as if it was a um an anti osteophyte and even register all of that. Um But uh again, it was just for demonstration purposes, but now we're, we're moving on to the tibia here uh to essentially do the same thing uh regarding creating the virtual map of the um the proximal tibia. Um Again, as you said, George Great Points is trying to stay on implant or bone and I do spend a lot more time here really. Um getting as much of the proximal Tiia as possible in order to give the robot as much information as possible to help me. Um When planning the case in the next few steps, if it is a P S poly in there, do you think you have to cut the post off um to register the tibia or do you think there's some way of leaving the post on there? Yeah, you can, you can absolutely leave it on there. Um You know, just not, you know, necessarily map it. Uh just go around there. You can see those blue marks that come up there. Those are the, the points that the robot is asking for um in order to create the uh most reliable um virtual map here and you can see that the, the um virtual map is jumping around here as I give the robot more information um and uh deciding what the most optimal uh model would be uh for the case moving forward. Yeah, it's an efficient way of doing it, you know, you're not clicking through multiple points. Um It's a, it's a quick registration step uh here that you're making look pretty good and it looks like on the tibia, you're registering a little more uh than maybe on a primary knee as well. Any particular points on the tibia that you think are crucial to registering. Uh Yeah, I mean, I, I, I certainly the, the points that are necessary, the deepest and um and deepest points medium and louder. But really here, I think is key, what we just did is actually utilizing the power of special points to uh give us a general idea of where the implant and bone interface is at. Um And you'll see later on, um, we will uh accommodate or at least, uh take that into account when planning for the surgery here. So before we get too far along here, I, I wanna, you know, point out a very important point here is that this is the first implant planning screen and immediately I make necessary adjustments in the setting of revision different than that of a um a primary setting. I I immediately change the slope because the slope in the um uh the legion uh R K system needs to be at zero. And so I automatically make that change there. I also change the flexion to approximately three degrees of flexion. And then I also pay attention to the various vagus uh positioning of the implant itself. Um You know, we're still relying on the intermediate canals for some level of fixation. And so therefore, we have some level of constraint there. We certainly uh my tolerances are a lot tighter in the setting of a revision in that um I won't necessarily go outside of a degree. Um Most in vari aus uh because of um uh the the canal being the constraint. And then the last thing that I do here is actually I automatically plan for the the implant uh excuse me, the polyethylene thickness uh to be a 13. And that's to plan for the three millimeter difference between a primary leg revision base plate with that measures 2.3 millimeters and the revision base plate that is 5.5 millimeters. So we have to account for that additional three millimeters of thickness on the revision base plate. And that's why I go straight to a 13 and that's planning for a 10 poly that makes perfect sense. Or if you were a nine poly sort of person, you could plan for a 12 and that would also be fine depending on your preference. But you have to account for the extra thickness of this base plate. Now, I see you're taking the knee through a stress range of motion. Uh looks like your technique was to stress that on hand. Uh There's a lot of different ways to do that. I use the Zera tractor myself. Um And there is a tension or uh as well. Do you have any issues getting your various V to uh stress in deep reflection? Right? How, how are you doing that? Yeah, certainly. I mean that, that's, that's always the concern and you know, your amount of stress is different than my amount of stress and even between a Z retractor and PC L retractor or manually, they're, they're quite different, but certainly in deep flexion with a valgus stress, it's, it's not as difficult, but certainly with a various stress in deep flexion, it could be a little less reliable. But I do actually go back and forth. I will, um, stress and then restress and, um, many times over, um, to see, you know, what is giving me the most complete information. And that's really the power here is that this is really the few systems that will actually allow you to get a stress um uh capture of of objective data throughout the whole entire arc of motion. Whereas some other robotic technologies really only allow you in extension and inflection as well. I saw your balancing there. You were pretty much shooting for equal extension inflection gaps and you weren't really tight or loose an extension inflection. Is that kind of what you like for your balancing? Yeah, absolutely. Even in the primary setting, I I am a true gap balancer, I want an equal rectangular space, an extension and 90° of flexion. And so those are certainly always my goals. Now, if you know it's way outside of that, um say that there's a huge lateral laxity. Um I do still have those constraints of not um altering the, the verse vagus of the tibi or femur beyond using a degree. Then I we have to start thinking about releases um as we do in a typical revision setting. And so, um, there are some small nuanced differences, but fortunately in this situation, she had a reasonably balanced knee here, um, with some, uh, more laxity immediately. But, um, we, we got a little lucky on this case, that's for sure. Yeah. And you know, a lot of revisions, you have trouble catching up to your flexion gap. Uh, so if someone's extension gap is kind of ok, and they have a loose flexion gap, how can Corey help you get that more balanced potentially compared to manual instrumentation? Yeah, I mean, we'll hopefully talk about this even more down the uh rest of the video. But you know, it, it we are taking this is a fundamental change in how we think about uh revision surgery. I mean, so much of the past, we've focused on engaging the diaphysis of the femur and the diaphysis of the tibia and we're restricted with that space. And so um if we needed to fill the flexion space, then there comes in a poster offset that would be necessary or upsizing the femoral component. But you know, coy really allows us the ability to um you know, flex the component as appropriate within some constraints and then really understand objectively the amount of um flexion space tightness we engage uh with um you know, going up in size or flexing the coma component ever so slightly. Yeah, that sounds great. And also with the potential of keeping your joint line appropriately distal. I think a lot of revision total knee guys are going to raise the joint line, increasing their poly thickness. Hoping the extension gap will take the increased poly. You probably have to don't have to make those compromises uh when you have this amount of data. And it's just, it's just the having that objective information is absolutely key. Here. I see you did a safe thermal component removal with uh looked like a microsagittal saw and some flexible osteo toes. Uh What's your standard removal tools for you? Yeah. So um indeed, exactly as you said, uh I, I start off the implant, bone interface and, and utilize some toes. Um Then I actually love the uh renovation system that Smith and Nee offers where it uh it's a, I call it the spider monkey. And I got that from one of my fellowship attendings. Um but hooked that onto a femur and an extraction, you could do it on the tibi as well. It's actually an in line um extraction as opposed to if you're using a home run, for example, it may be causing a flu and you may take out more of the post your condos um than what you had intended for the tibia. Unfortunately, in this situation, um the reason why we're doing the surgery is uh because of how loose it was. And you can see you saw that it just popped right up and then I'll utilize a V cutter to essentially break up the um the cement mantle and then take it out um a piecemeal. And you can see the extent of what I suspect to be osteolysis. This patient did have a substantial amount of subsurface de elimination and um catastrophic damage to her medial um uh polyethylene. And so I think uh this has affected some of her uh osteolysis, particularly along the lateral condo here. And you can see this is just all filled with fibrous tissue, particularly poster lateral. And um even right now, I'm, I'm starting to think to myself, as we all do as revision surgeons, we start um thinking, OK, what type of augments are we gonna need here? And then just trying to get an idea of where the bone is at relative to um the defects or, and what our plan should be agree, you got to really define the bone and sometimes I've got all that fibrous tissue off the bone uh to really see what's there and what is not? Um I see that you're kind of moving ahead to at least some refinement or ephemeral bone removal here. So, tell us what's this initial step you're doing now that you've seen what bone is there, right? So now we're trying to get to more objective information of what the defects are. And so the first step here um is uh actually just painting away what the the remainder bone is relative to the plan anticipated plan for the implants. And so you can see here certainly uh relative to the plan I have a substantial defect in the red uh on the distal media and lateral, lateral greater than me. And certainly poster lotto as I mentioned earlier, but poster me, there appears to be enough bone where um I may not necessarily need an augment. And so I'm thinking this through my head and this is my first step just getting an idea of and you even at this point, you could just go straight to um milling away that post your media condo because that's where the plan calls for the final implant to sit. The second way here is actually utilizing the satellite dish I call and actually getting a numeric value the amount of um bone loss. So we're along the media from this little media, the condo and I'm seeing that it's about 345 millimeters of, of defect. And so I'm thinking in my mind, ok, distal media, we're gonna need at least a five millimeter augment to in order to create a a flat level surface, then I'll go over to the lateral conda. And you can see that that number is jumping around from 9 10 to you know, 13. And so at the deepest points, maybe 13 millimeters. So again, in my mind, I'm thinking I may need a 15 millimeter lateral augment in order to get a flat level surface. Unfortunately, we can't do the same thing as the software is now um with the poster condos. And that's where the next step is, is um uh is accounting for that utilizing special points. And so I switched back to collecting more um data points and then actually paint the surfaces distal and poste of the medium lot of thermal condos and actually um create a visual um uh reference of where the def effects are. So um there are four different ways that I'm counting for these uh defects with my own eyes, with the refinement with the numeric um satellite dish, and then also with um with these uh special points as well too. Um And again, just painting away all the or painting away somewhat is the wrong word. But um giving the uh computer more information as far as where the defects are, then we can actually switch to the um the cross sectional view. And then you can actually visualize in the top left corner there uh in the coronal plane uh where those defects are at. And so therefore, plan appropriately for the augment. So um you can see that um uh distal media there is certainly more bone remaining than distal lateral. And so you want to work your way from the smallest defect to the largest defect. And I generally work distal femur than to post ear femur following that. And so, in this case, I'm planning for a five millimeter um distal media augment and that actually accounts for 10 clicks. So that is um it's a half a millimeter per click. And so as I proximal the the implant, I ensure that I'm gonna be have the, the level of that surface beyond all of those um the visualized special points in order to create the the most level flat surface in this stage for the distal femur cut, I actually um plan for just um milling away just the distal femur and that there is an option. We went through that quite quickly, but I'm gonna select just, you can see here just um planning for uh executing just the distal femur cut. And again, I'm just focusing along the media, the condo here and um milling away the the bone again, accounting for that five millimeter augment. You can see that there's some ghost bone here um just deep to uh where excuse me, superficial to where the um the probe is. And there's an option where you can actually um eliminate all that purple by just the bottom left button. Um And we'll do that here shortly. Uh I do have a remaining uh cement plug from the uh previous lug of the implant. And that was also um preventing me from getting a very level surface here. Then we'll go back uh and try to create the most level surface along the um distal medial condo. Um and we end up creating a nice level surface there. Now, the red is actually where the champers are gonna be at. So obviously, uh there's gonna be uh what looks like defect, but all I'm really focusing on here is just that distal femur part here and that, that looks reasonably level to me now. So then we're gonna, when you did the extra 10 clicks, people are gonna watch this and say, did you take an extra five off the medial thermal con dial? So can you just be specific, you know how much bone did it actually resect? Can help the viewers rectify that quickly. George. I mean, that's such a great point because in the past, you know, with the traditionally instrument of revisions, I mean, we're talking about resecting 34 or five millimeters of bone in this situation at most, I probably resected a millimeter of bone along the distal medial. And so that is again with precision milling as uh what Corey robot is. Um we're, we're preserving a lot more bone. So I didn't necessarily take away five more millimeters. All I did was account for those defects and try to create a flat level surface. And so we, we moved on to the, the lateral condo here and as we saw, I was anticipating it being a 15 millimeter augment initially, but uh I proximal the joint or actually the planned implant um to account for a 10 millimeter augment. So I moved it up, uh another five more millimeters, which was another 10 more clicks. Um And you could see that um I, I'm actually created quite a level surface. If it was not enough of an augment, then you actually see a whole bunch of red pop up here. Um Because the uh the, the probe or actually the mill would actually be diving down um beyond that planned surface. And so here, um again, you know, in traditional instrument and knees, I would have gone immediately to just visualizing it. I would have ended up cutting uh that extra bone that not really necessary. I've created a nice level surface here and preserved as much bone as possible in your manual instrumentation workflow. Were you someone who pinned jigs to take extra bone off the femur or were you more of a freehand style, would you say? Oh yeah, I was still uh pretty reliant on jigs. Um uh I don't think I'm that good and uh my eyes aren't that good, I guess. Um But uh yeah, so I would always uh do it uh with the um pin jigs. My own frustration with pinning all those jigs is you'd go through the process of multiple, you know, episodes of instrumentation. And the end result is you'd barely take little nicks of bone off little places. It just seemed like a lot of work for not a lot of bone removal. And in this scenario, you really haven't opened a single manual jig at all just to point this out and you're preparing the bone with one instrument. Uh So it certainly has been a much more efficient way of doing it. And uh no doubt about it, I mean, it's, it's, it's really a game changing aspect again, just less stress on everybody. Um And I'm just using that one tool. Um What we did here is actually account for the post dealer um augments and, and again, post year immediately, we already knew that um we're not gonna necessitate any augments. And so I'm really focusing along the poster lateral um and she had uh quite a large defect. And again, I had thought it would possibly be about a 10 millimeter augment, but it turned out I proximal, excuse me, answer the plan to account for five millimeter poster lateral augment. Um And it seemed to uh go beyond the level of the um the special points that I collected. And you can see that I'm really focusing on the bottom left portion of the screen and try to uh create a level poster uh lateral platform for the implant to sit when we're seeing these colors blue and green. In this case about how much bone are you? Is that representing that you're trying to take away from that area? You know, so certainly um the purple is like greater than three millimeters and forgive me if I'm wrong. I think the blue is 2 to 3 and then green is about a millimeter. So or less than uh less than a half a millimeter on the green. So I think that's true. So um you're really not, not taking too much bone here, you're just cleaning up that poster lateral surface. Yeah. In, in this situation, she had some extra bone growth along the poster lateral condo. So I actually switched here to what's called the rogue mode. And again, this is one of the great uh aspects of having an extra instrument in your room is that you have a wonderful powerful mill. Um You know, there are a lot of revision settings where I have a um a high speed burr um to have a more controlled bone resection, but it's right there for you to, to utilize at all times. And you'll see that I use that um to at least initiate the preparation for the box. And so, you know, one thing I didn't mention earlier is that when we had the initial plan, uh I really try to create a home base, right? So everybody on my team uh has a very good idea of where the home base is. And so that's the initial plan that we were um planned for. And then as we adjust the implants uh to account for augment, um that's what we're constantly referencing back to is ensuring that I place the plan back to that home base. Um And it's been important for us to do that. And I do know that Smith and F V does have some uh sterile um charts that you can actually um jot down and take notes in the case of the amount of rest section that is planned. And so that can be your home base method as well and you can see if that makes sense. Yeah, you wouldn't want to plan for augments and these extra clicks that we just talked about, you gotta put it back to your home plan, like you said, that's a great point, Steve. Um Now tell me what's going on here. Yeah, so as I mentioned earlier, we didn't, we don't necessarily need any augments here. And so I'm resecting the um the poster medial bone to create a level surface. And then we uh don't obviously need any augments of sorts along the anterior flange. And so just creating a freshening cut or mill along the anterior aspect of the femur um in, in order to create a, a level surface there. Um And that's it, the, the entire femoral preparation as far as uh cuts are concerned are finished now. And as you had mentioned earlier, I didn't use uh I only use one instrument for that entire process, but here, as I mentioned earlier, we're, we're preparing for the boss. And so I initiate that um this is me showing the plan augments with a five distal media and a 10 distal lateral with a five millimeter uh poster lateral augment. Um And I was just mentioning, you know, preparing for the center, I actually will place this um media lateral to, to identify where the most ideal position along the distal femur it can sit. Um and then actually utilize the mill to create a, a starting hole for the um uh for the boss here. And you'll see that I'll actually just freehand the boss reamer to its appropriate depth. When you go to place that initial trial, how have you found the fit has been with the trial on the femur, the cosmesis? Sure. I mean, I, I think it's better than uh any uh mechanically or excuse me, traditionally in intermittent a revision or that I've done in the past. I mean, it, it is really changed the expectations that I have for that in this situation. It wasn't perfect uh but certainly quite snug uh media lateral and also into your poster, a very little give there. Um in order to papare for the the box, I, I do pin it in place because I don't want that wobbling around. And I'm pretty uh uh judgmental of uh you know how my cut surfaces are both vitally and uh uh posterior as well. Um And so, uh I've again been quite pleased with how the trials and certainly the final implants have been sitting. And then how about the prepared bond surface? You know, one of the number one causes of failure of a revision knee for aseptic loosening is repeat aseptic loosening. Do you think when you bur the end of the bone, it helps with your repeat cement or digit? I think it's a, it's a great question and I don't know if we have uh, the answers for that completely. I know that there are, there's some that are currently looking into that, um, of actually looking at it on the microscopic level of what we're doing for that, that interface and whether or not uh the cement or digitization is gonna be dramatically different than that of a saw blade. But certainly, you know, questions that we all would love to have answers to, for sure. Yeah, I'm hopeful that that will be true. Uh A lot of the epica or bone is sclerotic and almost dead that we're trying to cement into uh hence the need for a zone two meta Vasil fixation for a lot of these cases. Uh But I am curious and hopefully the data will support this notion that uh when you're preparing the end of the bone and you have a fresher bone surface that there is at least some potential uh for better in inner digit of the rather into the sclerotic bone that you, that you may have otherwise. Um Now moving on to the tibia looks like you're subluxing the tibia forward for exposure. Um And what is your technique for the tibia team? Yeah, so just the same as as the femur. So the first step is in refinement mode is actually to just visually define the uh amount of bone loss that's been encountered uh through the pathology. In addition to implant extraction, in this case, it was just removing cement. And as we saw on the preoperative radiographs, it had dropped in the virus. So certainly relative to the plan, there's certainly more bone loss immediately um than compared lateral. Unfortunately, in this case, I I did over model some bone laterally and you'll see later that it that's not necessarily real bone. But then again, as with the femur, I, I take the next step of utilizing special points and actually creating another visual reference of where the defects are at. So I try to um paint as much of the the proxima surface. Um and as we move forward to the actual planning, um accounting for that is um placing the implant beyond the level of those dots, those pink dots in order to create the most level uh surface possible. So again, I'm focusing now to the um bottom left screen, I'm looking at it in the sagittal plane and you can see that the level of the planned implant is a few millimeters above where the defects are at. Now, there's two ways of going about it. I can just plan straight off for five millimeter augment or play the millimeter game is actually dropping this down every two clicks and then accounting for that for a greater poly in this situation, I chose to go straight to plan for a five millimeter proximal tibia augment. And that was a, a total of 10 clicks of bringing the plan down further. And you can see that as I scroll through in the sado view, um the level of the surface will be beyond the level of all of those um those pink dots. And I I I think this is really key is that, you know, again, I keep mentioning this is we're working on a sub millimeter level now, right in the past, I'm just eyeballing things to 34 or five millimeters. And you know, that's really been a game changing um aspect of, of using this tool for revisions. How do you make the decision between going to the augment and just cutting more tibia to have a flat tibia? Um Do you have a number in mind or, or a gut feeling? How do you make this inter operative decision? Yeah, I guess it, it's just whatever I'm feeling at that time. And if I I I don't like looking at an x-ray with a big old plastic space in between. And in this situation, if I just went up five millimeters on the poly plan, uh that would have been a 15 millimeter poly. And um and also you also have to think about the fin augments too, right? If you had a five millimeter augment, you lose a little bit of rotational stability because the fins aren't necessarily prepared as if you had the full uh fins on there. So all these things are keeping in mind, one nice thing about the legion A K system is that the um the proximity augments actually have built in fins for the 10 millimeter augment. So if you ever get that far, um you will still have the rotational control with the um the uh 10 millimeter augments as well. It is a nice feature and uh even your stem isn't sitting as deep and things like that. Uh So when, when you're sitting up, you know, way high like that, so having those spins for rotational control is a, is a nice feature. Um Any issues uh with augment placement, ann ization of a tibial cone, uh any trick tricks or tips to get cones and augments to fit, doesn't matter. It always happens. I mean, any issues there, Steve. No, I mean, I, I think it's, it's um you know, I guess it's about where you place the cone. I mean, certainly you need to be uh in my opinion, subsurface uh just in case if you need to break it up later on, there is a small uh bone implant uh interface to, to work around. Um But no, I mean, you can utilize any uh proximal to v augment with really any cone. Um I guess the real question is, is how much uh at what point do you use a cone George, I mean, what are your um your indications for uh cone use? Yes, sure. You know, at least at our institution, um you know, we've not uh restricted the use of cones, we're able to kind of use them as we see fit, which is great uh from a cost standpoint. So uh every revision uh that we do is getting a tibial cone. Um but only for every tibial cone we put in um or 18 tibial cones we put in, there's only one thermal cone utilized. So I think that's somewhat standard amongst institutions is the utilization of thermal cones is a bit less uh than tibial cones. Uh How about you? Yeah. No, I, I, I'm exactly the same. I mean, I, I would say 99% of my uh revision cases uh utilize and capitalize on that biologic and growth of the, of a cone on the tibia side. Um But certainly on the femur side, it's more about 10 to 20% of the time. And certainly for manual instrumentation, if, if you are using a tibial cone, kind of cutting off the top of that as a flat surface can be a useful tip. Um which is not really necessary when you have the core robot as you just demonstrated. Uh But if you are going to do it manually, that can be um a good trick, so to speak. Uh So here in the video, it looks like you've been happy with your tibial trial. Um, and you're starting to do some cone preparation. I think. I also saw when you put the trials and you hadn't used a stem yet. Um, is that gonna come later or, you know, at what point do you, are you gonna start putting stems onto your revision knee? Yeah. So that's the very last step for my, um, it's, I've kind of flipped it on its head whereas that's the first step in a traditionally instrument in a revision. Whereas, um, yeah, I'm not relying upon the diaphysis again, I'm, I'm really uh taking everything out of the diaphysis and putting it back into a joint where I feel is you have the most control and uh the less restrictions, of course. Um And so yes, um my trials don't have any cones. I mean, excuse me, don't have any stems in then we'll, at a, at the very end we um uh approximate the, the size of the canal planning for a short, uh 120 millimeter stem on both the femur and the tibia for this cone preparation. You know, you've got this five millimeter meaty augment. So your cone really needs to be flushed with the medial bone and you should be beneath your lateral bone by five. Is that correct? Yes. Yeah. So sorry. I think that's what the, the question you're asking. And certainly, yeah, you need to be below the level of the augment. So you know, in this situation, it's a both a medial and lateral uh wedge augment. So it's along the entire of the, of the approximal tibia. OK. I must have missed that. So you've got, tell me your Tibby augments one more time, you've got a medial and you've got a block augment or you have just a media augment. Yeah. So the, the Tibby augments come in wedges, so a medial and lateral. So they're separate, but they're both five in this situation here. OK. Excellent, excellent. Uh So this is uh an initial trial. No stems here. Is that right? Steve? Still? Yeah, still, still. No uh stems in there. So you can see that there's some jog of the, the tibia implant. But certainly if there were stems in there, there would uh it would be quite more, much more stable there and then not seeing a semi constrained polyethylene trial. What, what is that trial that you have? Yeah. So that's a great point. Georgia. I mean, now it's, we've really uh this has really changed the way that um uh what type of constraint I put in in revisions? I mean, I I I may not be the greatest surgeon in the world, but I feel like on the order of 60 to 70% of my revision cases, I was putting in a constrained poly. Um I've talked to other surgeons and my number is quite high, but now I've completely flipped it on its head. I mean, I very rarely utilize a constrained poly in, in the setting of revision because the balance is so good here. Uh The um uh the, the vas vagus constraint is just not necessary. Um And it's so well balanced and I think I'm seeing here, you know, man, I, I, I don't know if I can even do a primary knee that feels like this as good as this. And why do you think that is? I mean, in other words, for me, in a revision setting, there can be a lot of mid flexion instability and I feel like I'm needing a wider post. How does Corey with this revision need system? Why is that better? You know, why does that happen? Yeah, I mean, I, I, I think you're one the precision and, and planning ability is, is there like we've never had it before and then now you can also have uh objectified information where you're actually seeing in that mid flexion uh arc, uh what it's actually doing. And, and certainly if you go back into the my plan, they actually, it looked like that I had some mid flexion tightness uh through 30 to 60 degrees of, of motion. And so, you know, just having that information and it, it really does help me sleep better at night to, to uh but I, I have the same concerns and worries about uh doing a traditionally instrument and knee really changing the joint line and really messing with what's going on in mid flexion space. Yeah, I think it's so helpful to keep the joint line distal. Uh I think the mid flexion laxity at 30 degrees is actually more of a function of your extension gap. And in these revisions, it's so easy to raise the joint line. It's getting closer to your collateral insertions and you're getting that mid flexion and stability and it's very hard to fix mid flexion and stability with manual instrumentation. With this robotic platform, you can keep the joint line distal, maintain your flexion stability. But then you can also catch up with your flexion gap because you know how much you need to post to your eyes, your femur, it's very hard. Every one of those is predicated on a previous assumption that's very difficult to make because you don't have all the data manually to your point. You know, we've got the data to make interoperate decisions to even fix this mid, mid flexion and stability where you don't need a semi constrained post. Uh That was a little bit long winded um As you're continuing to, to build your trial implant better Georgia and that, that was, that was perfect. Yeah. Um So here you've got your cone and now I think you mentioned this, tell me your fixation preference method or your, your style of fixation for your, for your tibia here. Yeah. So it certainly we drop the cone down and then we'll fully cement the uh the, the tibial implant. Um I usually try to use as good of a cement technique as possible. Utilize a cement restrictor, pressurize the canal. Uh The video jump beyond all of that, but I really spend some time to ensure that I really pressurize that canal um and then remove the excess cement. Um My P A is applying pressure uh as for as long as possible until we go to the femur. And the same thing really fill up the canal. Again, we jump through, pressurizing the canal itself uh and then cement the entire femur as well. Same thing uh third generation cement technique and um uh ensuring it is good and pressurized as as possible here. Now you put some pins through the bone here. So when you're cementing is the cement gonna come out through your pin holes and what's going on with that? That's a great point. I mean, uh this is another thing about pin placement is um if you end up staying within the area of the um the trackers, then you do have to account for the fact that cement can extravasate out. So I think no matter if I'm using the information or not from the robot or I am I I leave those pins in uh just to not allow for any cement extravasation to occur. I think there, there probably is an alternate technique. Uh If your pins are in the zone of where your stem will be. You may be able to just back them up a little bit. It still will fill unicortical, uh you know where that cement would come out. It won't let it out and then you can remove the pin afterwards, maybe uh an alternate way of doing it. Um And tell us about your post op baseline data here. Yeah. So, uh the first step is to actually um objectify the the arc range of motion for the patient. She can hang to about 100 and 35 flex beyond 100 and 40 then uh taking it through the arc of motion, uh assessing the gap balancing. Uh and you could see applying a various stress and then we're talking less than a millimeter or so of gapping between media and lateral throughout the entire arc of motion. Um You know, this is what we're shooting for every single time. And you know, there's a little bit more tightness immediately relative to lateral and that that is perfect there. So I'm very happy with the end result and the overall balance that's, that's been achieved here. Do you remember what the polyethylene thickness was for this case? Yeah, so I ended up going to an 11. So the plan was for that uh 10 millimeters again, I had, I had it at 13, accounting for tibia implant thickness and then uh plan for 10 millimeters. So um I ended up uh going up to 11 just to add a little bit more tightness uh throughout the case, especially these older females, the, the, the soft tissues tend to stretch a little bit more. Um And so I just went up to 11. Very happy with uh how that felt throughout the arc of motion. Clearly, with the advent of robotics, it's decreased polyethylene uh variability. Do you think it's the same for revision as a primary or do you think you're still gonna be a little more variable with your poly thickness on a revision? Uh No, I I I think it's been the same really. I mean, what I plan um I am within a millimeter or two at most as far as the final polyethylene thickness, right? And that's still accounting for what my subjective feeling of what I'm shooting for versus what the objective data that is, is uh the robot is pro providing me. So, but in general, I, no, even in revision settings, I still am within about a millimeter or two. What the the plan was you had mentioned earlier in the video um that you really weren't going off neutral mechanical axis, too much on the tibial side, think you'd mention a degree per potentially, you know, the thermal side uh for legion, the, you know, the stem is fixed to the femur at six degrees. Um Do you make any changes bears vagus uh to the thermal coronal alignment or, or not too much. Yeah, that's a fantastic point too. Right? Is understanding that we're already set at 6°. So, uh all of my patients get preoperative standing alignment films as well too. So I, I get an idea of what their true um overall distal thermal angle is. Um And so if I feel like that, uh they need a little bit more vari then I, I'll do that um in order to create as neutral mechanical access as possible. But that's the beauty here is that you can really, you know, um customize what you're trying to shoot here for, you know, in the past, particularly in the revision setting. I mean, I, I can't tell you that I'm within a millimeter of, of resection nor a degree and that's been proven over and over in different investigations. Just the human eye. What are we humanly capable of doing now, somebody that's done, you know, 10,000 knee arthroplasty and, you know, 5000 revisions that they're gonna know that better than I. But, uh for me, um just having this objective tool is, is really been quite helpful and really reassuring for me too. A few other things. Um Do you feel like this workflow with robotics will talk about your x-rays too? Do you feel like it's helped with efficiency? Are you time neutral? You know, where do you think you are with your, your, your time? Yeah. So in, in the primary setting, uh no, doubt there's some learning curve, but I think no more so or uh no less than most other um uh robotic systems. But as time has gone along, I am certainly faster utilizing um a robotic system in the revision setting. Um There really wasn't much of a, of a learning curve, I think at this point. Um I'm actually faster utilizing um uh the robot. Um But there's no doubt there are times where um the first few cases you just want to make sure that you're doing the steps appropriately. Um But now I'm, I'm certainly faster even in the revision setting as well. These x-rays are looking good. I've got great cement mantel, up and down uh cone. You can see your tibial augments there. You've restored the poster kind of offset the thermal component. Patella's tracking. Well, do you have any critiques of your own work here, Steve? Oh yeah, I think it looks pretty good. Um uh That's certainly a little bit of extension uh on the fem on the fem component. Um But uh you know, again, that's part of the beauty here is, is that if I needed to fill the flexion space more, and I and I was unsure about the flexion gap, then, you know, really account for that and, you know, maybe even go down on the, the femoral component, uh stem diameter and then flex the component even further and utilize. Um uh I really open up the entire canal, um, to whatever is necessary. But I'm, I'm quite happy with how this a case turned out and she's now approximately, uh, four weeks post up. Uh, she came back, uh, she was discharged on post up day one. Uh, she ambulated about 500 ft the morning after surgery. This was the last case of the day, um, left the afternoon post upper day number one. Um, she returned in at her two week visit. Um, she's walking unassisted. Uh, no, can a walker. Um, and, uh, it's certainly having some pain but nothing is far less than, uh, what I think. Uh, I normally get in revisions. And again, I think a lot of it is, is I'm, I'm doing a lot less soft tissue work and releases and that's certainly even the case in the setting of primaries as well. Thank you so much to Smith and nephew for hosting this and to doctor Steve Nishiyama for an excellent job demonstrating this Corey robot. It's been a pleasure to be with you. And, uh, if you have any further questions, please don't hesitate to ask any Smith and nephew, staff or your local representation, uh, about Corey robot and primary and, or revision knee replacement. Thank you so much. Thank you, everyone.
